Fingerprint image capturing device and fingerprint image capturing module thereof

ABSTRACT

A fingerprint image capturing module includes a light-emitting element, a light-splitting element, a first light-reflecting element, a second light-reflecting element, a lens assembly and a fingerprint image sensing element, characterized in that: a projection light beam generated by the light-emitting element is reflected by the light-splitting element and the first light-reflecting element in sequence to form an illumination light beam that passes through a light-transmitting element and is projected onto a fingerprint of a finger, the illumination light beam is reflected by the finger to form an image light beam that is reflected by the first light-reflecting element, the image light beam sequentially passes through the light-splitting element and the lens assembly and is projected onto the fingerprint image sensing element through the second light-reflecting element, and the fingerprint image sensing element receives the image light beam to obtain a fingerprint image of the fingerprint of the finger.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The instant disclosure relates to an image capturing device and an imagecapturing module thereof, and more particularly to a miniaturizedfingerprint image capturing device and a miniaturized fingerprint imagecapturing module thereof.

2. Description of Related Art

In general, the fingerprint recognition apparatus reads informationabout people's fingerprints by scanning their fingerprints on theapparatus. For example, when the finger touches a fingerprint touchplate, several light sources emit light for the lens to capture thefingerprint image. Because the angles between the lens and fingers, andthe angles between the light source and fingers have to be adjusted tospecific angles for achieving total reflection so that the fingerprintrecognition apparatus can capture a clear and distinct fingerprint.Therefore, the optical fingerprint recognition apparatus in the priorart are large in size and cannot be miniaturized.

SUMMARY OF THE INVENTION

One aspect of the instant disclosure relates to a miniaturizedfingerprint image capturing device and a miniaturized fingerprint imagecapturing module thereof.

One of the embodiments of the instant disclosure provides a fingerprintimage capturing device, comprising: a circuit substrate, an externalcasing, a light-transmitting element and a fingerprint image capturingmodule. The external casing is disposed on the circuit substrate,wherein the external casing has a top opening formed on the top sidethereof. The light-transmitting element is disposed on the externalcasing to enclose the top opening of the external casing. Thefingerprint image capturing module is disposed inside the externalcasing, wherein the fingerprint image capturing module includes alight-emitting element, a light-splitting element, a firstlight-reflecting element, a second light-reflecting element, a lensassembly and a fingerprint image sensing element. The light-emittingelement is electrically connected to the circuit substrate. Thelight-splitting element is disposed in front of the light-emittingelement. The first light-reflecting element is disposed beside one sideof the light-splitting element and separated from the light-splittingelement by a first predetermined distance, wherein the firstlight-reflecting element has a light-reflecting curved surface. Thesecond light-reflecting element is disposed beside another side of thelight-splitting element and separated from the light-splitting elementby a second predetermined distance. The lens assembly is disposedbetween the light-splitting element and the second light-reflectingelement. The fingerprint image sensing element is disposed under thesecond light-reflecting element and electrically connected to thecircuit substrate. Whereby, a projection light beam generated by thelight-emitting element is reflected by the light-splitting element andthe light-reflecting curved surface of the first light-reflectingelement in sequence to form an illumination light beam that first passesthrough the light-transmitting element and then is projected onto afingerprint of a finger, the illumination light beam is reflected by thefinger to form an image light beam that is projected onto thelight-reflecting curved surface and then is reflected by thelight-reflecting curved surface, the image light beam first sequentiallypasses through the light-splitting element and the lens assembly andthen is projected onto the fingerprint image sensing element through thesecond light-reflecting element, and the fingerprint image sensingelement receives the image light beam to obtain a fingerprint image ofthe fingerprint of the finger.

More precisely, the light-splitting element has a light-splittingportion and a first positioning portion connected to the light-splittingportion and positioned inside the external casing, the light-reflectingelement has a base portion, an electroplated light-reflecting layerformed on the base portion, and a second positioning portion connectedto the base portion and positioned inside the external casing, and thelight-reflecting curved surface of the first light-reflecting element isformed on the electroplated light-reflecting layer, wherein the lensassembly includes an optical lens composed of at least two lens unitsand an aperture stop adjacent to the optical lens, each lens unit has alens portion and a third positioning portion connected to the lensportion and positioned inside the external casing, and the aperture stophas a screen portion and a through hole passing through the screenportion.

Another one of the embodiments of the instant disclosure provides afingerprint image capturing module, comprising: a light-emittingelement, a light-splitting element, a first light-reflecting element, asecond light-reflecting element, a lens assembly and a fingerprint imagesensing element. The light-splitting element is disposed in front of thelight-emitting element. The first light-reflecting element is disposedbeside one side of the light-splitting element and separated from thelight-splitting element by a first predetermined distance, wherein thefirst light-reflecting element has a light-reflecting curved surface.The second light-reflecting element is disposed beside another side ofthe light-splitting element and separated from the light-splittingelement by a second predetermined distance. The lens assembly isdisposed between the light-splitting element and the secondlight-reflecting element. The fingerprint image sensing element isdisposed under the second light-reflecting element. Whereby, aprojection light beam generated by the light-emitting element isreflected by the light-splitting element and the light-reflecting curvedsurface of the first light-reflecting element in sequence to form anillumination light beam that first passes through a light-transmittingelement and then is projected onto a fingerprint of a finger, theillumination light beam is reflected by the finger to form an imagelight beam that is projected onto the light-reflecting curved surfaceand then is reflected by the light-reflecting curved surface, the imagelight beam first sequentially passes through the light-splitting elementand the lens assembly and then is projected onto the fingerprint imagesensing element through the second light-reflecting element, and thefingerprint image sensing element receives the image light beam toobtain a fingerprint image of the fingerprint of the finger.

Yet another one of the embodiments of the instant disclosure provides afingerprint image capturing module comprising a light-emitting element,a light-splitting element, a first light-reflecting element, a secondlight-reflecting element, a lens assembly and a fingerprint imagesensing element, characterized in that: a projection light beamgenerated by the light-emitting element is reflected by thelight-splitting element and a light-reflecting curved surface of thefirst light-reflecting element in sequence to form an illumination lightbeam that first passes through a light-transmitting element and then isprojected onto a fingerprint of a finger, the illumination light beam isreflected by the finger to form an image light beam that is projectedonto the light-reflecting curved surface and then is reflected by thelight-reflecting curved surface, the image light beam first sequentiallypasses through the light-splitting element and the lens assembly andthen is projected onto the fingerprint image sensing element through thesecond light-reflecting element, and the fingerprint image sensingelement receives the image light beam to obtain a fingerprint image ofthe fingerprint of the finger.

More precisely, the projection light beam generated by thelight-emitting element is reflected by the light-splitting element toform a first reflected light beam that is projected on the firstlight-reflecting element, the first reflected light beam is reflected bythe light-reflecting curved surface of the first light-reflectingelement to form a second reflected light beam that first passes throughthe light-transmitting element and then is projected onto thefingerprint of the finger, wherein both the projection light beam andthe first reflected light beam are substantially horizontal moving lightbeams, and the second reflected light beam is a substantially verticalmoving light beam.

More precisely, the second reflected light beam is reflected by thefinger to form a first fingerprint image light beam that first passesthrough the light-transmitting element and then is projected on thelight-reflecting curved surface and is reflected by the light-reflectingcurved surface, the first fingerprint image light beam sequentiallypasses through the light-splitting element and the lens assembly to forma second fingerprint image light beam that is projected onto the secondlight-reflecting element, the second fingerprint image light beam isreflected by the second light-reflecting element to form a thirdfingerprint image light beam that is projected onto the fingerprintimage sensing element, and the fingerprint image sensing elementreceives the third fingerprint image light beam to obtain thefingerprint image of the fingerprint of the finger, wherein both thefirst fingerprint image light beam and the third fingerprint image lightbeam are substantially vertical moving light beams, and the secondfingerprint image light beam is a substantially horizontal moving lightbeam.

Therefore, the fingerprint image capturing device and the fingerprintimage capturing module can be miniaturized due to the arrangement of thelight-emitting element, the light-splitting element, the firstlight-reflecting element, the second light-reflecting element, the lensassembly and the fingerprint image sensing element, thus the fingerprintimage capturing device and the miniaturized fingerprint image capturingmodule can be applied to any miniaturization electronic product.

To further understand the techniques, means and effects of the instantdisclosure applied for achieving the prescribed objectives, thefollowing detailed descriptions and appended drawings are herebyreferred to, such that, and through which, the purposes, features andaspects of the instant disclosure can be thoroughly and concretelyappreciated. However, the appended drawings are provided solely forreference and illustration, without any intention to limit the instantdisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows one perspective, schematic view of the fingerprint imagecapturing device according to the first embodiment of the instantdisclosure;

FIG. 2 shows a cross-sectional view taken along the section line A-A ofFIG. 1;

FIG. 3 shows a cross-sectional view taken along the section line B-B ofFIG. 1;

FIG. 4 shows a top, cross-sectional, schematic view of the fingerprintimage capturing device according to the second embodiment of the instantdisclosure; and

FIG. 5 shows a lateral, cross-sectional, schematic view of thefingerprint image capturing device according to the second embodiment ofthe instant disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments of “a fingerprint image capturing device and afingerprint image capturing module thereof” of the instant disclosureare described. Other advantages and objectives of the instant disclosurecan be easily understood by one skilled in the art from the disclosure.The instant disclosure can be applied in different embodiments. Variousmodifications and variations can be made to various details in thedescription for different applications without departing from the scopeof the instant disclosure. The drawings of the instant disclosure areprovided only for simple illustrations, but are not drawn to scale anddo not reflect the actual relative dimensions. The following embodimentsare provided to describe in detail the concept of the instantdisclosure, and are not intended to limit the scope thereof in any way.

First Embodiment

Referring to FIG. 1 to FIG. 3, FIG. 2 shows a cross-sectional view takenalong the section line A-A of FIG. 1, and FIG. 3 shows a cross-sectionalview taken along the section line B-B of FIG. 1. The first embodiment ofthe instant disclosure provides a fingerprint image capturing device S,comprising: a circuit substrate 1, an external casing 2, alight-transmitting element 3 and a fingerprint image capturing module G,and the fingerprint image capturing module G is disposed inside theexternal casing 2. The fingerprint image capturing module G includes alight-emitting element 4, a light-splitting element 5, a firstlight-reflecting element 6, a second light-reflecting element 7, a lensassembly 8 and a fingerprint image sensing element 9.

Firstly, referring to FIG. 1 and FIG. 3, the external casing 2 isdisposed on the circuit substrate 1, and the external casing 2 has a topopening 20 formed on the top side thereof. Because the size of thelight-transmitting element 3 is substantially the same as the topopening 20, the light-transmitting element 3 can be disposed on theexternal casing 2 to enclose the top opening 20 of the external casing2. For example, the circuit substrate 1 may be a board having apredetermined circuit layout formed thereon in advance. The externalcasing 2 may be made of opaque material. The light-transmitting element3 may be a transparent board made of glass or plastic material.

Moreover, referring to FIG. 2 and FIG. 3, the light-emitting element 4is electrically connected to the circuit substrate 1. Thelight-splitting element 5 is disposed in front of the light-emittingelement 4. The first light-reflecting element 6 is disposed beside (nextto) one side of the light-splitting element 5 and separated from thelight-splitting element 5 by a first predetermined distance, and thefirst light-reflecting element 6 has a light-reflecting curved surface60. More precisely, the light-emitting element 4 (such as LED) istransversely placed on the circuit substrate 1, thus the projectionlight beam L generated by the light-emitting element 4 is moved along asubstantially transverse direction or substantially horizontal to thetop surface of the circuit substrate 1. The light-splitting element 5(or called a light-separating plate) has a light-splitting portion 50and a first positioning portion 51 connected to the light-splittingportion 50 and positioned inside the external casing 2, and thelight-splitting portion 50 of the light-splitting element 5 issubstantially vertically disposed on the circuit substrate 1 and infront of the light-emitting element 4. The light-reflecting element 6has a base portion 60, an electroplated light-reflecting layer 61 formedon the base portion 60 by electroplating, and a second positioningportion 62 connected to the base portion 60 and positioned inside theexternal casing 2, and the light-reflecting curved surface 610 of thefirst light-reflecting element 6 is just then on the electroplatedlight-reflecting layer 61. Of course, the light-reflecting curvedsurface 610 can be formed by other ways than electroplating.

Furthermore, referring to FIG. 2 and FIG. 3, the second light-reflectingelement 7 is disposed beside (next to) another side of thelight-splitting element 5 and separated from the light-splitting element5 by a second predetermined distance. The lens assembly 8 is disposedbetween the light-splitting element 5 and the second light-reflectingelement 7. The fingerprint image sensing element 9 is disposed under thesecond light-reflecting element 7 and electrically connected to thecircuit substrate 1. More precisely, the lens assembly 8 includes anoptical lens 8A composed of at least one lens unit 80 (for example,there are two lens units 80 shown in FIG. 80) and an aperture stop 8B(or a pupil) adjacent to the optical lens 8A, each lens unit 80 has alens portion 800 and a third positioning portion 801 connected to thelens portion 800 and positioned inside the external casing 2, and theaperture stop 8B has a screen portion 810 and a through hole 811 passingthrough the screen portion 810. The fingerprint image sensing element 9may be any type of fingerprint image sensor according to differentrequirement.

Hence, referring to FIG. 2 and FIG. 3, a projection light beam Lgenerated by the light-emitting element 4 is reflected by thelight-splitting element 5 and the light-reflecting curved surface 610 ofthe first light-reflecting element 6 in sequence to form an illuminationlight beam R that first passes through the light-transmitting element 3and then is upwardly projected onto a fingerprint f of a finger F. Theillumination light beam R is formed as a wide-angle illumination thatcan be widely projected onto the fingerprint f of the finger F due todesign of the light-reflecting curved surface 610 of the firstlight-reflecting element 6, thus most of area of the fingerprint f ofthe finger F can be illuminated by the illumination light beam R. Theillumination light beam R is reflected by the finger F to form an imagelight beam M that is downwardly projected onto the light-reflectingcurved surface 610 and then is reflected by the light-reflecting curvedsurface 610. The image light beam M first sequentially passes throughthe light-splitting element 5 and the lens assembly 8 and then isdownwardly projected onto the fingerprint image sensing element 9through the second light-reflecting element 7 (i.e., the image lightbeam M is downwardly projected onto the fingerprint image sensingelement 9 after the image light beam M is reflected by the secondlight-reflecting element 7). Whereby, the fingerprint image sensingelement 9 can receive the image light beam M to obtain a fingerprintimage of the fingerprint f of the finger F that is touching thelight-transmitting element 3.

More precisely, referring to FIG. 2 and FIG. 3, the projection lightbeam L generated by the light-emitting element 4 is reflected by thelight-splitting element 5 to form a first reflected light beam R1 thatis forwardly projected on the first light-reflecting element 6 (as shownin FIG. 2). The first reflected light beam R1 is reflected by thelight-reflecting curved surface 610 of the first light-reflectingelement 6 to form a second reflected light beam R2 that first passesthrough the light-transmitting element 3 and then is upwardly projectedonto the fingerprint f of the finger F (as shown in FIG. 3). It is worthnoting that, both the projection light beam L and the first reflectedlight beam R1 are substantially horizontal moving light beams that canbe moved along a substantially horizontal direction, and the secondreflected light beam R2 is a substantially vertical moving light beamthat can be moved along a substantially vertical direction.

More precisely, referring to FIG. 2 and FIG. 3, the second reflectedlight beam R2 is reflected by the finger F (i.e., the second reflectedlight beam R2 goes back through the finger F) to form a firstfingerprint image light beam M1 that first passes through thelight-transmitting element 3 and then is downwardly projected on thelight-reflecting curved surface 610 and is reflected by thelight-reflecting curved surface 610 (as shown in FIG. 3). The firstfingerprint image light beam M1 sequentially passes through thelight-splitting element 5 and the lens assembly 8 to form a secondfingerprint image light beam M2 that is projected onto the secondlight-reflecting element 7 (as shown in FIG. 2 or FIG. 3). The secondfingerprint image light beam M2 is reflected by the secondlight-reflecting element 7 to form a third fingerprint image light beamM3 that is downwardly projected onto the fingerprint image sensingelement 9 (as shown in FIG. 3). Whereby, the fingerprint image sensingelement 9 can receive the third fingerprint image light beam M3 toobtain the fingerprint image of the fingerprint f of the finger F thatis touching the light-transmitting element 3. It is worth noting that,both the first fingerprint image light beam M1 and the third fingerprintimage light beam M3 are substantially vertical moving light beams thatcan be moved along a substantially vertical direction, and the secondfingerprint image light beam M2 is a substantially horizontal movinglight beam that can be moved along a substantially horizontal direction.

It is worth mentioning that the fingerprint image capturing device S canbe miniaturized due to the arrangement of the light-emitting element 4,the light-splitting element 5, the first light-reflecting element 6, thesecond light-reflecting element 7, the lens assembly 8 and thefingerprint image sensing element 9, thus the miniaturized fingerprintimage capturing device S can be applied to any miniaturizationelectronic product such as cell phone.

Second Embodiment

Referring to FIG. 4 and FIG. 5, the second embodiment of the instantdisclosure provides a fingerprint image capturing module G, comprising:a light-emitting element 4, a light-splitting element 5, a firstlight-reflecting element 6, a second light-reflecting element 7, a lensassembly 8 and a fingerprint image sensing element 9. Thelight-splitting element 5 is disposed in front of the light-emittingelement 4. The first light-reflecting element 6 is disposed beside oneside of the light-splitting element 5 and separated from thelight-splitting element 5 by a first predetermined distance, and thefirst light-reflecting element 6 has a light-reflecting curved surface610. The second light-reflecting element 7 is disposed beside anotherside of the light-splitting element 5 and separated from thelight-splitting element 5 by a second predetermined distance. The lensassembly 8 is disposed between the light-splitting element 5 and thesecond light-reflecting element 7. The fingerprint image sensing element9 is disposed under the second light-reflecting element 7.

Hence, referring to FIG. 4 and FIG. 5, a projection light beam Lgenerated by the light-emitting element 4 is reflected by thelight-splitting element 5 and the light-reflecting curved surface 610 ofthe first light-reflecting element 6 in sequence to form an illuminationlight beam R that first passes through the light-transmitting element 3and then is upwardly projected onto a fingerprint f of a finger F. Theillumination light beam R is formed as a wide-angle illumination thatcan be widely projected onto the fingerprint f of the finger F due todesign of the light-reflecting curved surface 610 of the firstlight-reflecting element 6, thus most of area of the fingerprint f ofthe finger F can be illuminated by the illumination light beam R. Theillumination light beam R is reflected by the finger F to form an imagelight beam M that is downwardly projected onto the light-reflectingcurved surface 610 and then is reflected by the light-reflecting curvedsurface 610. The image light beam M first sequentially passes throughthe light-splitting element 5 and the lens assembly 8 and then isdownwardly projected onto the fingerprint image sensing element 9through the second light-reflecting element 7 (i.e., the image lightbeam M is downwardly projected onto the fingerprint image sensingelement 9 after the image light beam M is reflected by the secondlight-reflecting element 7). Whereby, the fingerprint image sensingelement 9 can receive the image light beam M to obtain a fingerprintimage of the fingerprint f of the finger F that is touching thelight-transmitting element 3.

More precisely, referring to FIG. 4 and FIG. 5, the projection lightbeam L generated by the light-emitting element 4 is reflected by thelight-splitting element 5 to form a first reflected light beam R1 thatis forwardly projected on the first light-reflecting element 6 (as shownin FIG. 4). The first reflected light beam R1 is reflected by thelight-reflecting curved surface 610 of the first light-reflectingelement 6 to form a second reflected light beam R2 that first passesthrough the light-transmitting element 3 and then is upwardly projectedonto the fingerprint f of the finger F (as shown in FIG. 5). The secondreflected light beam R2 is reflected by the finger F (i.e., the secondreflected light beam R2 goes back through the finger F) to form a firstfingerprint image light beam M1 that first passes through thelight-transmitting element 3 and then is downwardly projected on thelight-reflecting curved surface 610 and is reflected by thelight-reflecting curved surface 610 (as shown in FIG. 5). The firstfingerprint image light beam M1 sequentially passes through thelight-splitting element 5 and the lens assembly 8 to form a secondfingerprint image light beam M2 that is projected onto the secondlight-reflecting element 7 (as shown in FIG. 4 or FIG. 5). The secondfingerprint image light beam M2 is reflected by the secondlight-reflecting element 7 to form a third fingerprint image light beamM3 that is downwardly projected onto the fingerprint image sensingelement 9 (as shown in FIG. 5). Whereby, the fingerprint image sensingelement 9 can receive the third fingerprint image light beam M3 toobtain the fingerprint image of the fingerprint f of the finger F thatis touching the light-transmitting element 3.

It is worth mentioning that the fingerprint image capturing module G canbe miniaturized due to the arrangement of the light-emitting element 4,the light-splitting element 5, the first light-reflecting element 6, thesecond light-reflecting element 7, the lens assembly 8 and thefingerprint image sensing element 9, thus the miniaturized fingerprintimage capturing module G can be applied to any miniaturizationelectronic product such as cell phone.

In conclusion, the fingerprint image capturing device S and thefingerprint image capturing module G can be miniaturized due to thearrangement of the light-emitting element 4, the light-splitting element5, the first light-reflecting element 6, the second light-reflectingelement 7, the lens assembly 8 and the fingerprint image sensing element9, thus the fingerprint image capturing device S and the miniaturizedfingerprint image capturing module G can be applied to anyminiaturization electronic product.

The aforementioned descriptions merely represent the preferredembodiments of the instant disclosure, without any intention to limitthe scope of the instant disclosure which is fully described only withinthe following claims. Various equivalent changes, alterations ormodifications based on the claims of the instant disclosure are all,consequently, viewed as being embraced by the scope of the instantdisclosure.

What is claimed is:
 1. A fingerprint image capturing device, comprising:a circuit substrate; an external casing disposed on the circuitsubstrate, wherein the external casing has a top opening formed on thetop side thereof; a light-transmitting element disposed on the externalcasing to enclose the top opening of the external casing; and afingerprint image capturing module disposed inside the external casing,wherein the fingerprint image capturing module includes: alight-emitting element electrically connected to the circuit substrate;a light-splitting element disposed in front of the light-emittingelement; a first light-reflecting element disposed beside one side ofthe light-splitting element and separated from the light-splittingelement by a first predetermined distance, wherein the firstlight-reflecting element has a light-reflecting curved surface; a secondlight-reflecting element disposed beside another side of thelight-splitting element and separated from the light-splitting elementby a second predetermined distance; a lens assembly disposed between thelight-splitting element and the second light-reflecting element; and afingerprint image sensing element disposed under the secondlight-reflecting element and electrically connected to the circuitsubstrate; wherein a projection light beam generated by thelight-emitting element is reflected by the light-splitting element andthe light-reflecting curved surface of the first light-reflectingelement in sequence to form an illumination light beam that first passesthrough the light-transmitting element and then is projected onto afingerprint of a finger, the illumination light beam is reflected by thefinger to form an image light beam that is projected onto thelight-reflecting curved surface and then is reflected by thelight-reflecting curved surface, the image light beam first sequentiallypasses through the light-splitting element and the lens assembly andthen is projected onto the fingerprint image sensing element through thesecond light-reflecting element, and the fingerprint image sensingelement receives the image light beam to obtain a fingerprint image ofthe fingerprint of the finger.
 2. The fingerprint image capturing deviceof claim 1, wherein the light-splitting element has a light-splittingportion and a first positioning portion connected to the light-splittingportion and positioned inside the external casing, the light-reflectingelement has a base portion, an electroplated light-reflecting layerformed on the base portion, and a second positioning portion connectedto the base portion and positioned inside the external casing, and thelight-reflecting curved surface of the first light-reflecting element isformed on the electroplated light-reflecting layer, wherein the lensassembly includes an optical lens composed of at least two lens unitsand an aperture stop adjacent to the optical lens, each lens unit has alens portion and a third positioning portion connected to the lensportion and positioned inside the external casing, and the aperture stophas a screen portion and a through hole passing through the screenportion.
 3. The fingerprint image capturing device of claim 1, whereinthe projection light beam generated by the light-emitting element isreflected by the light-splitting element to form a first reflected lightbeam that is projected on the first light-reflecting element, the firstreflected light beam is reflected by the light-reflecting curved surfaceof the first light-reflecting element to form a second reflected lightbeam that first passes through the light-transmitting element and thenis projected onto the fingerprint of the finger, wherein both theprojection light beam and the first reflected light beam aresubstantially horizontal moving light beams, and the second reflectedlight beam is a substantially vertical moving light beam.
 4. Thefingerprint image capturing device of claim 3, wherein the secondreflected light beam is reflected by the finger to form a firstfingerprint image light beam that first passes through thelight-transmitting element and then is projected on the light-reflectingcurved surface and is reflected by the light-reflecting curved surface,the first fingerprint image light beam sequentially passes through thelight-splitting element and the lens assembly to form a secondfingerprint image light beam that is projected onto the secondlight-reflecting element, the second fingerprint image light beam isreflected by the second light-reflecting element to form a thirdfingerprint image light beam that is projected onto the fingerprintimage sensing element, and the fingerprint image sensing elementreceives the third fingerprint image light beam to obtain thefingerprint image of the fingerprint of the finger, wherein both thefirst fingerprint image light beam and the third fingerprint image lightbeam are substantially vertical moving light beams, and the secondfingerprint image light beam is a substantially horizontal moving lightbeam.
 5. A fingerprint image capturing module, comprising: alight-emitting element; a light-splitting element disposed in front ofthe light-emitting element; a first light-reflecting element disposedbeside one side of the light-splitting element and separated from thelight-splitting element by a first predetermined distance, wherein thefirst light-reflecting element has a light-reflecting curved surface; asecond light-reflecting element disposed beside another side of thelight-splitting element and separated from the light-splitting elementby a second predetermined distance; a lens assembly disposed between thelight-splitting element and the second light-reflecting element; and afingerprint image sensing element disposed under the secondlight-reflecting element; wherein a projection light beam generated bythe light-emitting element is reflected by the light-splitting elementand the light-reflecting curved surface of the first light-reflectingelement in sequence to form an illumination light beam that first passesthrough a light-transmitting element and then is projected onto afingerprint of a finger, the illumination light beam is reflected by thefinger to form an image light beam that is projected onto thelight-reflecting curved surface and then is reflected by thelight-reflecting curved surface, the image light beam first sequentiallypasses through the light-splitting element and the lens assembly andthen is projected onto the fingerprint image sensing element through thesecond light-reflecting element, and the fingerprint image sensingelement receives the image light beam to obtain a fingerprint image ofthe fingerprint of the finger.
 6. The fingerprint image capturing moduleof claim 5, wherein the projection light beam generated by thelight-emitting element is reflected by the light-splitting element toform a first reflected light beam that is projected on the firstlight-reflecting element, the first reflected light beam is reflected bythe light-reflecting curved surface of the first light-reflectingelement to form a second reflected light beam that first passes throughthe light-transmitting element and then is projected onto thefingerprint of the finger, wherein both the projection light beam andthe first reflected light beam are substantially horizontal moving lightbeams, and the second reflected light beam is a substantially verticalmoving light beam.
 7. The fingerprint image capturing module of claim 6,wherein the second reflected light beam is reflected by the finger toform a first fingerprint image light beam that first passes through thelight-transmitting element and then is projected on the light-reflectingcurved surface and is reflected by the light-reflecting curved surface,the first fingerprint image light beam sequentially passes through thelight-splitting element and the lens assembly to form a secondfingerprint image light beam that is projected onto the secondlight-reflecting element, the second fingerprint image light beam isreflected by the second light-reflecting element to form a thirdfingerprint image light beam that is projected onto the fingerprintimage sensing element, and the fingerprint image sensing elementreceives the third fingerprint image light beam to obtain thefingerprint image of the fingerprint of the finger, wherein both thefirst fingerprint image light beam and the third fingerprint image lightbeam are substantially vertical moving light beams, and the secondfingerprint image light beam is a substantially horizontal moving lightbeam.
 8. A fingerprint image capturing module comprising alight-emitting element, a light-splitting element, a firstlight-reflecting element, a second light-reflecting element, a lensassembly and a fingerprint image sensing element, characterized in that:a projection light beam generated by the light-emitting element isreflected by the light-splitting element and a light-reflecting curvedsurface of the first light-reflecting element in sequence to form anillumination light beam that first passes through a light-transmittingelement and then is projected onto a fingerprint of a finger, theillumination light beam is reflected by the finger to form an imagelight beam that is projected onto the light-reflecting curved surfaceand then is reflected by the light-reflecting curved surface, the imagelight beam first sequentially passes through the light-splitting elementand the lens assembly and then is projected onto the fingerprint imagesensing element through the second light-reflecting element, and thefingerprint image sensing element receives the image light beam toobtain a fingerprint image of the fingerprint of the finger.
 9. Thefingerprint image capturing module of claim 8, wherein the projectionlight beam generated by the light-emitting element is reflected by thelight-splitting element to form a first reflected light beam that isprojected on the first light-reflecting element, the first reflectedlight beam is reflected by the light-reflecting curved surface of thefirst light-reflecting element to form a second reflected light beamthat first passes through the light-transmitting element and then isprojected onto the fingerprint of the finger, wherein both theprojection light beam and the first reflected light beam aresubstantially horizontal moving light beams, and the second reflectedlight beam is a substantially vertical moving light beam.
 10. Thefingerprint image capturing module of claim 9, wherein the secondreflected light beam is reflected by the finger to form a firstfingerprint image light beam that first passes through thelight-transmitting element and then is projected on the light-reflectingcurved surface and is reflected by the light-reflecting curved surface,the first fingerprint image light beam sequentially passes through thelight-splitting element and the lens assembly to form a secondfingerprint image light beam that is projected onto the secondlight-reflecting element, the second fingerprint image light beam isreflected by the second light-reflecting element to form a thirdfingerprint image light beam that is projected onto the fingerprintimage sensing element, and the fingerprint image sensing elementreceives the third fingerprint image light beam to obtain thefingerprint image of the fingerprint of the finger, wherein both thefirst fingerprint image light beam and the third fingerprint image lightbeam are substantially vertical moving light beams, and the secondfingerprint image light beam is a substantially horizontal moving lightbeam.